The objective of this work is to determine whether prenatal exposure to low levels of mercury is related to the frequency of births of children with congenital disorders. Lead exposure also leads to congenital disorders which are similar to those associated with mercury. Because of this, a lead study parallel to the mercury study will be undertaken to better define the risk associated with each metal. Specifically this will be done my comparing estimates of prenatal mercury and lead exposure of a group of pediatric patients with diagnosed developmental disabilities of unknown origin with that of a group of such patients with congenital health problems of known origin while controlling for other factors which have congenital effects. Existing data indicates that maternal blood lead and mercury levels remain relatively constant with time under specific conditions and therefore fetal exposure to these metals can be estimated by measuring current levels. Mothers of patient treated at the Division of Developmental Disabilities of the University of Iowa Pediatrics Department will serve as subjects. Life style and demographic factors with teratogenic potential will be controlled for by using questionaires and treating them as covariables in the statistical analysis. Blood mercury analysis will be done using cold reduction with sodium borohydride and atomic absorption spectrophotometry. That for lead will involve chelation and separation with an organic solvent and flame spectrophotometry. The results of a preliminary study by Kuntz et al. (1981) suggested that untoward obstetric events are related to low blood mercury levels. That work, if true, could have considerable impact because it has been shown that similar blood levels can be related to the presences of dental amalgams. The proposed study is intend to provide a basis determining whether such a health risk exists.